水溶性量子点荧光探针用于帕珠沙星的含量测定

文章采用荧光光谱和紫外光谱研究了CdTe量子点(CdTe QDs)与广谱抗菌药物帕珠沙星的相互作用。结果表明，随着帕珠沙星浓度的增加，CdTe QDs荧光强度有规律的降低，但通过透射电镜图对QDs及加入帕珠沙星后的QDs进行比较，发现QDs仍然均一单分散，表明反应的作用机理可能是帕珠沙星促使QDs表面键合的有机分子发生变化，在Cd空位表现出的表面缺损上形成了碲氧复合物，致使荧光猝灭。因此该反应可作为一种新颖的快速检测帕珠沙星含量的方法。在一定条件下，帕珠沙星溶液的浓度与量子点荧光强度成线性关系，线性范围为10.0～850 μg·mL-1，相关系数r为0.995 4，检测限(S/N=3)为3.254×10-3 μg·mL-1。药物对量子点的猝灭常数为2.188×104 L·mol-1。应用到冻干粉针剂和氯化钠注射液中帕珠沙星的含量测定，所得结果与标示量一致。该方法较常用检测方法具有简便、快捷、灵敏、线性范围宽的优点，并有望进一步开展发药物体内显像及作用机理的研究。

Quantitative Determination of Pazufloxacin Using Water-Soluble Quantum Dots as Fluorescent Probes

The quantum dots (QDs) synthesized in aqueous solution have more advantages than those synthesized in organic solution, for drugs always act on the biological systems. In addition, the CdTe QDs surface-bound TGA molecules can not only enhance the fluorescence intensity, but also improve the stability of quantum dots, which makes the integrate of quantum dots and the organism easier. The present paper studied on the interaction of CdTe quantum dots, which were synthesized in aqueous solution with pazufloxacin, the forth generation of quinoloines drugs by fluorescence spectrum and absorption spectrum. The results showed that the fluorescence intensity of CdTe quantum dots decreased regularly with increasing concentration of pazufloxacin. No absorption band was observed in the 400-700 nm wavelength range for pazufloxacin, so the quenching effect of pazufloxacin on the fluorescence of CdTe QDs was not due to an inner filter resulting from the absorption of the emission wavelength by pazufloxacin. No obvious change was observed for the CdTe QDs absorption spectra before and after adding pazufloxacin, and a blue-shift or red-shift of the fluorescence emission spectra was also not seen when the concentration of pazufloxacin was changed from 10.0 to 850 microg x mL(-1), which also meant that CdTe QDs had not aggregated or become smaller after adding pazufloxacin. And the CdTe QDs, which had a good dispersion characteristic, uniform shape and centralized distribution whether in or out of pazufloxacin solution, were observed by the images of transmission electron microscopy. This indicated that the mechanism of the reaction was likely to be that the changes of surface-bound organic molecules of QDs, the --COOH chemical bond, were induced by pazufloxacin, and the Te-oxygen complex was formed at the Cd surface vacancies. Based on the quenching of the fluorescence of CdTe QDs by pazufloxacin, a rapid, novel and specific method for pazufloxacin determination was proposed. In the optimum conditions, pazufloxacin concentration versus quantum dots fluorescence gave a linear response with an excellent 0. 995 4 correlation coefficient, between 10.0 and 850 micorg x mL(-1). The limit of detection (S/N=3) was 3. 254 x 10(-3) microg x mL. And the quenching constant could be obtained, which was 2.188 x 10(4) L x mol(-1). The RSD value about fluorescence quenching of CdTe QDs by 5 groups of 50 microg x mL(-1) concentration of pazufloxacin was 0.3%. The contents of pazufloxacin in freeze-dried powder injection and sodium chloride injection were determined by the proposed method and the results agreed with the claimed values. The proposed method is much more convenient, rapid, sensitive and has a much broader linear range than other methods, such as HPLC, HPCE and UV etc. It is hopeful to contribute to the development of the studies of pharmacal imaging and the reaction mechanisms of medicines in vivo further.